Spitzer Space Telescope - Archive Research Proposal #40210


LMC Planetary Nebulae: IR Luminosity Functions, AGB Halos, and a Spitzer Search
for New Candidates

Principal Investigator: Martin Cohen
           Institution: University of California, Berkeley

     Technical Contact: Martin Cohen, University of California, Berkeley

Co-Investigators: 
Joseph Hora, Harvard-Smithsonian, CfA, USA                            
Quentin Parker, Macquarie University, Australia                       
Warren Reid, Macquarie University, Australia                          

Science Category: evolved stars/pn/sne 
Dollars Approved: 100456 

Abstract:
One of the longest standing and most difficult astronomical problems is to
determine the relation between the birth mass of stars and the mass left when
they die. Most mass lost by 1-8 solar mass stars occurs during rapid evolution
on the asymptotic giant branch (AGB). Towards the end of its life, a star sheds
its outer layers as a planetary nebula (PN) but little matter is expelled. The
hot, remnant star ionizes the PN and previous ejecta. PN ionized gas is ~0.1
solar masses so most of a progenitor star's mass must be dispersed into a large
faint envelope: an AGB halo. Techniques exist to measure stellar core mass,
ionized nebula and faint halo once a PN is identified and its halo recognized,
but only if we know the PN's distance. The Large Magellanic Cloud (LMC) distance
is well established while its geometry implies all its PNe share this distance.
We propose a combined IR, optical and radio study of all known LMC PNe observed
by the SAGE Legacy project. The enhanced products, due for release in 2007-8,
will provide photometry of unresolved PNe. Fluxes of resolved PNe will be
extracted from IRAC/ MIPS images. Of 693 LMC PNe observed by SAGE, 233 were
found optically prior to SAGE and 460 newly found by Co-Is Reid and Parker in an
ultra-deep H-alpha survey of the LMC's central 25sq.deg. Their survey is a
unique database of optical spectra and H-alpha images in which 280 new, faint,
AGB halos have also been discovered. Our goals are to: seek IR matches to AGB
halos and estimate total dust masses of their PNe; combine these with Gemini/VLT
optical spectra of ~30 PN central stars, their shells and halos to provide an
unrivaled sample of PNe for which we will derive masses of total ejecta and
stellar core to define an independent initial-final mass relation. We will also
enlarge the LMC census by seeking PNe in SAGE source lists by their IR colors
and create new IR and radio luminosity functions for LMC PNe to compare with our
unprecedentedly complete new [OIII] and H-alpha luminosity functions.